Many communications networks, such as subscription-based access networks, utilize gateway devices to provide user devices with access to a network. Such a network access server (“NAS”) may enforce policies involving functions such as, for example, traffic filtering, quality of service (QoS) assurance, and usage monitoring for charging. These policies may be delivered to the NAS for enforcement by a central policy server with access to subscriber information and network operator configurations. In some deployments, multiple NASs may be utilized for different functions. For example, a primary NAS may provide network access and enforce QoS requirements, while an auxiliary NAS may perform deep packet inspection (DPI) to perform application-specific traffic management such as limiting file sharing traffic or enriching HTTP with subscriber information.